That's because she was....*deep breath* A TRAVELING COMPANION from the start. That was how it was always intended to be.
How many times does this have to be repeated? Koharu is NOT a traveling companion. This is the story of Ash and Go.
You're making the exact mistake I told you to avoid: stop treating Koharu as the next Iris/Dawn/May etc and expecting her to have the same level of relevance when the series has made it quite clear that she does not.
I definitely agree. I want Koharu to have more character development, but I can’t see her becoming a traveling companion (at least not yet) since the marketing so far has only focused on Ash & Go traveling together
Personally, I feel her first episode would most likely be a “day in the life” scenario, that focuses on Koharu’s daily routine, establish her personal status quo, and give more insight as to why she’s so reluctant of everything that goes on.
Then, they’d have a Kanto-based episode where Ash & Go need to investigate something at Koharu’s school, where we learn more about her personal life, explain her relationship with Go, and find out a little more about Go’s past. They could also have Ash & Go battle Team Rocket & somehow drag Koharu into the problem of the day so she can see first hand the kind of stuff they usually have to deal with.
After that, a situation comes up where Koharu ends up filling in for Ash or Go on a mission either in Kanto, Johto, Hoenn, or Sinnoh (either by choice or by accident for comedy). She’ll shrug the Adventure off by the end of the episode but admit that it was a little fun.
Eventually, by either the halfway point or the end of the second season, Koharu will have more snippets of development, realize that she wants to go on adventures to, & then becomes a full-fledged traveling companion (or at least a substitute one whenever Ash or Go can’t come)
For me it's just wishful thinking since I love her voice actress
that and the fact that everyone’s so used to a female protagonist because of the previous series